Lung cancer treatment is currently based on surgery, chemotherapy and radiotherapy. Chemotherapy plays a very important role in the treatment of lung cancer as a systemic therapy. Many patients with intermediate to advanced lung cancer are often unable to tolerate chemotherapy due to poor physical status or the presence of multiple coexisting diseases. The TOPICAL study showed that erlotinib (Troche) is suitable for non-small cell lung cancer patients who are not suitable to receive chemotherapy. Similar drugs include gefitinib (ERSA), which are two of the more widely used targeted drugs in clinical practice, known as epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI). It has been proved that the efficiency of TKI can be increased to more than 80% by EGFR testing. For patients with positive EGFR mutation, TKI has the advantages of high efficiency and low toxicity. In addition, the current domestic charitable drug donation campaign has greatly reduced the financial burden of patients, and eligible patients who take a certain percentage of TKI drugs at their own expense can enjoy free drugs for life, which undoubtedly makes a great contribution to the prognosis of lung cancer.